In a known form of precision heavy duty indexer such as disclosed in U.S. Pat. No. 3,941,014, the indexing member is accurately and securely locked to the indexer housing by annular rows of axially interfitting radially extending teeth of form such as to eliminate axial, circumferential, and radial play in all indexed positions and to prevent transmission of torque loads on the indexing member to the indexing member drive means and to prevent transmission of radial loads on the indexing member to the indexing member-housing bearings. However, in such indexer the indexing member is axially movable with respect to the housing to engage and disengage the aforesaid teeth thus to lock said indexing member in indexed position and to unlock said indexing member for indexing to the next position. Hence, when said indexing member is in locked position, axial load thereon imposes additional compressive load on the engaged teeth.
In another known form of indexer as disclosed in U.S. Pat. No. 3,877,322, a diaphragm-type disc brake has its inner peripheral portion fixed to the indexing member and has its outer peripheral portion laterally flexed into frictional gripping engagement between the indexer housing and a hydraulically-actuated ring. However, in this form of indexer large axial and radial loads on the indexing member may impose severe axial and radial loads on the indexing member-housing bearings and large torque loads on the indexing member may impose severe shear loads on the locking pin of the indexing member drive means.